Vibration - what it is, it's importance and why we focus on vibration

What is vibration?

Vibration of a particle, object or body is movement back and forth about a position of equilibrium.

(an object is in equilibrium when a state of rest or the sum of external forces exerted on the object equals zero)

Why vibration is important?

These are the main reasons why we focus of vibration measurements and control. Throughout this website, you will appreciate that everything we do, will relate to vibration in some shape or form.

Human exposure to vibration

Exposure to high mechanical vibrations for too long a period results has health effects on humans, and can lead to adverse medical conditions. Medical conditions like whole hand arm and body vibration. (Hand-Arm-Vibration-Syndrome is also known as white finger or white finger syndrome.)

The Vibration at Work Regulations 2005 has more information on the exposure limits and durations. Companies should reference this regulation for safe operation of equipment. The HSE enforces this regulation, and the employer should enforce it too.

The European Physical Agents Directive 2002/44/EC also prescribes minimal exposure requirements. Enforced throughout Europe.

The regulations introduce an:

  • exposure action value of 2.5m.s-2 A(8). This is the level at which employers should introduce technical prevention measures.

  • exposure upper limit value of 5.0m.s-2 A(8). Do not exceed this limit.

If your equipment or machinery have unfavourable levels, our vibration consultants can improve, redesign and refine the equipment to have more favourable behaviour.

Please see our engineering services for further information

Vibration as the source of noise

We improve equipment and machinery by design to quieten or lessen the noise radiated from all products, equipment and machinery. We refine products so that they are less harmful to the operator and less noisy to the surroundings.

We minimize noise pollution to protect the environment. Not only to meet industrial standards, regulations and legislations; because it is the right thing to do.

As the source of noise, mitigating noise levels can be through vibration control. Designing surfaces to vibrate at lower amplitudes, will mitigate noise.

Our vibration consultants have investigated noise sources in housing, construction and in the automotive industry.

Noise is ever present in our daily lives, and is the source of sound and noise. The audible spectra for humans is between 20Hz and 20kHz. If the sound levels are very high, it becomes health threatening to humans.

(Different animal species are susceptible to frequency bandwidths broader than that for people. Hence, justifying the importance of mitigating noise levels emanated in the environment.)

Our work includes measurement, assessments, analysis, modelling, bench marking and design. Here are a few brief descriptions of our work:

  • finite element modelling of structures in vehicles to reduce noise radiation

  • transfer path analysis

  • BS 8233
  • bench marking of vehicles to understand their NVH and dynamic behaviour

  • acoustics measurements for residential and commercial dwellings

  • structural measurements, experimental modal analysis on the physical system to determine natural frequencies and mode shapes, to understand at which frequency the resonances occur, updating of the model etc.

Vibration isolation using anti-vibration (AV) mounts

The effectiveness of vibration isolation can only truly be confirmed with measurements either side of the isolation mechanism, i.e. AV mounts or anti-vibration mounts, to determine the vibrations transmitted through the AV mounts.

To peform this assessment, the amplitude and frequency of the vibration is not adequate. The phase angle of the measurements on either side is also important. As it is pertinent to know the direction of the motion on either side of the mount; whether it is in phase or out of phase in order to understand the exact transmissibility.

But the motion could originate from structural bending and is discussed on the structural dynamics page

References